https://urgentcomm.com/wp-content/themes/ucm_child/assets/images/logo/footer-new-logo.png
  • Home
  • News
  • Multimedia
    • Back
    • Multimedia
    • Video
    • Podcasts
    • Galleries
    • IWCE’s Video Showcase
    • Product Guides
  • Commentary
    • Back
    • Commentary
    • Urgent Matters
    • View From The Top
    • All Things IWCE
    • Legal Matters
  • Resources
    • Back
    • Resources
    • Webinars
    • White Papers
    • Reprints & Reuse
  • IWCE
    • Back
    • IWCE
    • Conference
    • Special Events
    • Exhibitor Listings
    • Premier Partners
    • Floor Plan
    • Exhibiting Information
    • Register for IWCE
  • About Us
    • Back
    • About Us
    • Contact Us
    • Advertise
    • Terms of Service
    • Privacy Statement
    • Cookie Policy
  • Related Sites
    • Back
    • American City & County
    • IWCE
    • Light Reading
    • IOT World Today
    • Mission Critical Technologies
    • TU-Auto
  • In the field
    • Back
    • In the field
    • Broadband Push-to-X
    • Internet of Things
    • Project 25
    • Public-Safety Broadband/FirstNet
    • Virtual/Augmented Reality
    • Land Mobile Radio
    • Long Term Evolution (LTE)
    • Applications
    • Drones/Robots
    • IoT/Smart X
    • Software
    • Subscriber Devices
    • Video
  • Call Center/Command
    • Back
    • Call Center/Command
    • Artificial Intelligence
    • NG911
    • Alerting Systems
    • Analytics
    • Dispatch/Call-taking
    • Incident Command/Situational Awareness
    • Tracking, Monitoring & Control
  • Network Tech
    • Back
    • Network Tech
    • Interoperability
    • LMR 100
    • LMR 200
    • Backhaul
    • Deployables
    • Power
    • Tower & Site
    • Wireless Networks
    • Coverage/Interference
    • Security
    • System Design
    • System Installation
    • System Operation
    • Test & Measurement
  • Operations
    • Back
    • Operations
    • Critical Infrastructure
    • Enterprise
    • Federal Government/Military
    • Public Safety
    • State & Local Government
    • Training
  • Regulations
    • Back
    • Regulations
    • Narrowbanding
    • T-Band
    • Rebanding
    • TV White Spaces
    • None
    • Funding
    • Policy
    • Regional Coordination
    • Standards
  • Organizations
    • Back
    • Organizations
    • AASHTO
    • APCO
    • DHS
    • DMR Association
    • ETA
    • EWA
    • FCC
    • IWCE
    • NASEMSO
    • NATE
    • NXDN Forum
    • NENA
    • NIST/PSCR
    • NPSTC
    • NTIA/FirstNet
    • P25 TIG
    • TETRA + CCA
    • UTC
Urgent Communications
  • NEWSLETTER
  • Home
  • News
  • Multimedia
    • Back
    • Video
    • Podcasts
    • Omdia Crit Comms Circle Podcast
    • Galleries
    • IWCE’s Video Showcase
    • Product Guides
  • Commentary
    • Back
    • All Things IWCE
    • Urgent Matters
    • View From The Top
    • Legal Matters
  • Resources
    • Back
    • Webinars
    • White Papers
    • Reprints & Reuse
    • UC eZines
    • Sponsored content
  • IWCE
    • Back
    • Conference
    • Why Attend
    • Exhibitor Listing
    • Floor Plan
    • Exhibiting Information
    • Join the Event Mailing List
  • About Us
    • Back
    • About Us
    • Contact Us
    • Advertise
    • Cookie Policy
    • Terms of Service
    • Privacy Statement
  • Related Sites
    • Back
    • American City & County
    • IWCE
    • Light Reading
    • IOT World Today
    • TU-Auto
  • newsletter
  • In the field
    • Back
    • Internet of Things
    • Broadband Push-to-X
    • Project 25
    • Public-Safety Broadband/FirstNet
    • Virtual/Augmented Reality
    • Land Mobile Radio
    • Long Term Evolution (LTE)
    • Applications
    • Drones/Robots
    • IoT/Smart X
    • Software
    • Subscriber Devices
    • Video
  • Call Center/Command
    • Back
    • Artificial Intelligence
    • NG911
    • Alerting Systems
    • Analytics
    • Dispatch/Call-taking
    • Incident Command/Situational Awareness
    • Tracking, Monitoring & Control
  • Network Tech
    • Back
    • Cybersecurity
    • Interoperability
    • LMR 100
    • LMR 200
    • Backhaul
    • Deployables
    • Power
    • Tower & Site
    • Wireless Networks
    • Coverage/Interference
    • Security
    • System Design
    • System Installation
    • System Operation
    • Test & Measurement
  • Operations
    • Back
    • Critical Infrastructure
    • Enterprise
    • Federal Government/Military
    • Public Safety
    • State & Local Government
    • Training
  • Regulations
    • Back
    • Narrowbanding
    • T-Band
    • Rebanding
    • TV White Spaces
    • None
    • Funding
    • Policy
    • Regional Coordination
    • Standards
  • Organizations
    • Back
    • AASHTO
    • APCO
    • DHS
    • DMR Association
    • ETA
    • EWA
    • FCC
    • IWCE
    • NASEMSO
    • NATE
    • NXDN Forum
    • NENA
    • NIST/PSCR
    • NPSTC
    • NTIA/FirstNet
    • P25 TIG
    • TETRA + CCA
    • UTC
acc.com

Interoperability


Sponsored

Benefits of End-to-End Vocoder Integration

Benefits of End-to-End Vocoder Integration

  • Written by Digital Voice Systems, Inc.
  • 28th May 2019

Introduction

Mission critical situations depend on wireless communication.  It is becoming increasingly popular to connect Land Mobile Radio (LMR) networks such as APCO Project 25 and Digital Mobile Radio (DMR) systems with commercial cellular LTE networks.  This can provide commercial and public safety users with more ways to communicate, while improving overall coverage areas, decreasing system costs and taking advantage of Internet data accessibility.  Yet, not all digital wireless systems are compatible with one another if they do not share the same voice coding technology, known as a vocoder.  Most modern LMR networks use the AMBE+2™ vocoder, whereas cellular LTE networks use the Advanced Multi-Rate (AMR) vocoder.  Transcoding from one vocoder to another can lead to the loss of intelligibility, increase delay and interfere with communications security, and should be avoided in favor of utilizing the same vocoder end-to-end in a communication system.


Figure 1: Popular Network Configuration

Transcoding for Interoperability

There are numerous systems in place today that transcode between the AMBE+2™ and AMR vocoders. These systems typically employ a gateway[1] function to do the transcoding as shown in Figure 1 and Figure 2.  By their nature, vocoders introduce loss, thereby degrading the original content.  During the process of transcoding from one vocoder to another, additional degradation occurs as has been shown in references [1] and [2].  In some cascading situations, multiple transcoding stages occur in tandem, which can result in severe loss of voice quality and intelligibility.

The best way to avoid transcoding between networks is for all talkers on a communication link to use the same vocoder.  AMBE+2™ is the only vocoder capable of being integrated into both LMR and LTE networks/devices.  The AMR vocoder in LTE networks cannot operate at the low data rates required by the narrow bandwidth requirements of digital radio networks.  This is where the AMBE+2™ vocoder has proven its mission critical worthiness over the past two decades.  Testing has shown that such end-to-end use of the AMBE+2™ vocoder preserves voice intelligibility without increasing delay and also supports end-to-end encryption.

Voice Quality and Intelligibility Testing

References [1] and [2] demonstrate the reduction in voice quality due to transcoding using Perceptual Evaluation of Speech Quality (PESQ) software which attempts to simulate the results of testing with subjective human listeners.  However, PESQ has many limitations including that it does not produce accurate results when testing speech containing background noise, and therefore is not appropriate in cases of noisy speech as commonly found in public safety and other mission critical applications.

The most accurate method for evaluating voice in noisy environments is to use human listeners.  The Modified Rhyme Test (MRT) is particularly useful for mission critical communication testing as it uses human listeners to test voice intelligibility i.e. one’s ability to comprehend what is being said.  This is in contrast to Mean Opinion Score (MOS) tests which focus on measuring overall voice quality, but may not reflect the level of intelligibility.  It is critically important that a firefighter, police officer or factory worker be understood by their co-workers.  Thus, MRT testing has more relevance to mission critical communications than do MOS tests.


Figure 2: Transcoding and End-to-End Flow

Modified Rhyme Test Results

DVSI conducted industry standard MRT tests to quantify the reduction of intelligibility caused by transcoding speech in the presence of typical background noise found in mission critical environments.  The tests were performed in accordance with ANSI/ASA standard S3.2.

The Modified Rhyme Test included transcoding between the 2450 bps AMBE+2™ vocoder used in P25 Phase II and DMR networks and the 4750 bps AMR vocoder used in LTE cellular systems.  Typical mission critical applications rely on RF performance including coverage and support for direct mode operations (see reference [3]) which influenced the bit rate selection for these tests.  The MRT tests compared end-to-end use of the AMBE+2™ vocoder (i.e. without transcoding) against speech transcoded between AMR and AMBE+2™.  The speech samples used in the testing included both male and female speakers mixed with firetruck panel pump, PASS alarm and street noise.

The MRT results showed that the AMBE+2™ vocoder end-to-end use produced significantly higher intelligibility than transcoding from AMR to AMBE+2™.  As shown in Figure 3, transcoding resulted in an average loss of more than 12% in intelligibility implying 12% fewer words would be understood in a transcoded communication as compared to the scenario where the AMBE+2™ vocoder is used end-to-end.  In a recent study (see reference [4]), an MRT score of 75% was considered a minimal speech intelligibility threshold, and as indicated in Figure 3, transcoding between AMR to AMBE+2™ did not meet this minimal threshold in any of the test conditions.  In mission critical applications, the 12% loss in intelligibility due to transcoding can easily make the difference between a high performing communications system and one that has significant impairments.


Figure 3: Intelligibility Test Results: Transcoding vs End-to-End AMBE+2™ Vocoder

End-to-End Vocoder Use Supports Encryption

Numerous agencies, utilities and corporations require encrypted communication to prevent criminal intercept, industrial espionage and to protect personal information.  The highest level of security requires the digital voice data to remain encrypted from one end of a communication link to another (i.e. end-to-end encryption).  However, transcoding requires the data to first be decrypted, and as a result transcoding between LMR and LTE network/devices is not possible with end-to-end encryption.  As a consequence, end-to-end encryption requires the AMBE+2™ vocoder to be used in both the LMR and LTE sides of the communication link.  The result is better communications security without the loss of intelligibility and added delay found in the transcoding approach.

Conclusion

Effective communication using interconnected LMR and LTE systems is challenged by ambient noise, difficult RF conditions and voice compression. Transcoding creates additional detrimental effects on intelligibility and should be avoided.  By utilizing the AMBE+2™ vocoder in both LMR and LTE systems transcoding is not used and communication intelligibility is maintained.

 

References

[1] U.S. Department of Homeland Security, Public Safety Communications Technical Report DHS-TR-PSC-13-0, (2013). Objective Speech Quality Estimates for Project 25/Voice over Long Term Evolution (P25/VoLTE) Interconnections.  Retrieved from:
https://www.dhs.gov/sites/default/files/publications/Objective%20Speech%20Quality%20Estimates_0.pdf

[2] J. Evans, (2014). Addressing Differences in Vocoder Technologies when Interfacing TIA-102 (P25) LMR Systems to Broadband Networks.  Retrieved from:
https://www.radioclubofamerica.org/wp-content/uploads/2015/11/04_Harris_RCA_Symposium_2014-11-22_jse_Rev4a.pdf

[3] Ericson,D. (2018). Public Safety Broadband Stakeholder Meeting Presentation.  Retrieved from: https://www.nist.gov/ctl/pscr/prose

[4] Letowski,T.R. & Scharine,A.A. (2017). Correlational Analysis of Speech Intelligibility Test and Metrics for Speech Transmission  ARL-TR-8227.  Retrieved from: https://www.arl.army.mil/arlreports/2017/ARL-TR-8227.pdf

[1] Gateway is used generically to refer to Media Gateways Session Border Controllers and similar devices that include media format transcoding.

Tags: In the field Land Mobile Radio Public-Safety Broadband/FirstNet Sponsored

Most Recent


  • AT&T FirstNet unleashes robotic dogs for emergency services
    AT&T is releasing robotic hounds from Ghost Robotics as part of the service provider’s FirstNet emergency responder service. In a blog, AT&T VP Lance Spencer explained that the robotic dogs will be connected to AT&T’s network and deployed for public safety, defense, federal and state agencies, local police and fire departments, and commercial customers. “Network-connected robotic dogs can deliver a […]
  • Federal agencies infested by cyberattackers via legit remote-management systems
    It has come to light that hackers cleverly utilized two off-the-shelf remote monitoring and management systems (RMMs) to breach multiple Federal Civilian Executive Branch (FCEB) agency networks in the US last summer. On Jan. 25, the Cybersecurity and Infrastructure Security Agency (CISA), National Security Agency (NSA), and Multi-State Information Sharing and Analysis Center (MS-ISAC) released […]
  • How 5G is making cities safer, smarter, and more efficient
    It’s a scenario we’ve all experienced: an ambulance with a blaring siren racing against time to get a person in medical distress to a hospital through traffic. What we don’t see is 5G connectivity enabling paramedics to communicate with hospital staff via video conference and coordinate care in real-time before arriving at the emergency room. […]
  • MCPTT interworking for critical communications
    The goal of mission-critical communication systems is to minimize the response time of first responders in emergency situations across several agencies. A dedicated push-to-talk button offers an efficient mechanism that simplifies the speaker-to-listener process to a minimum. This feature is useful when coordinating large group activities and to enable the instant flow of tactical status […]

Leave a comment Cancel reply

To leave a comment login with your Urgent Comms account:

Log in with your Urgent Comms account

Or alternatively provide your name, email address below:

Your email address will not be published. Required fields are marked *

Related Content

  • Open-source tools for the IoT ecosystem
  • New Orleans-area 911 center inks multiyear APEX deal with Carbyne to replace call-handling system
  • IoT connectivity spending climbs as COVID-19 cases decline
  • APCO, NENA, NASNA speakers cite ‘discussions’ to address NG911 funding issues

Commentary


How 5G is making cities safer, smarter, and more efficient

26th January 2023

3GPP moves Release 18 freeze date to March 2024

18th January 2023

Do smart cities make safer cities?

  • 1
6th January 2023
view all

Events


UC Ezines


IWCE 2019 Wrap Up

13th May 2019
view all

Twitter


UrgentComm

AT&T FirstNet unleashes robotic dogs for emergency services dlvr.it/ShW7p8

27th January 2023
UrgentComm

Federal agencies infested by cyberattackers via legit remote-management systems dlvr.it/ShVhn3

26th January 2023
UrgentComm

How 5G is making cities safer, smarter, and more efficient dlvr.it/ShVS1h

26th January 2023
UrgentComm

MCPTT interworking for critical communications dlvr.it/ShTm3P

26th January 2023
UrgentComm

Self-driving cars present terrorism risk, FBI director says dlvr.it/ShTTHx

26th January 2023
UrgentComm

UK Home Office officially will cut ESN ties with Motorola Solutions in December dlvr.it/ShNjfN

24th January 2023
UrgentComm

Newscan: Police software vendor breach exposes personal data, raid plans dlvr.it/ShN0q2

24th January 2023
UrgentComm

RT @IWCEexpo: We're so excited about our awesome list of speakers! Today we highlight Budge Currier, a 9-1-1 Branch Manager at CAL OES, res…

24th January 2023

Newsletter

Sign up for UrgentComm’s newsletters to receive regular news and information updates about Communications and Technology.

Expert Commentary

Learn from experts about the latest technology in automation, machine-learning, big data and cybersecurity.

Business Media

Find the latest videos and media from the market leaders.

Media Kit and Advertising

Want to reach our digital and print audiences? Learn more here.

DISCOVER MORE FROM INFORMA TECH

  • American City & County
  • IWCE
  • Light Reading
  • IOT World Today
  • Mission Critical Technologies
  • TU-Auto

WORKING WITH US

  • About Us
  • Contact Us
  • Events
  • Careers

FOLLOW Urgent Comms ON SOCIAL

  • Privacy
  • CCPA: “Do Not Sell My Data”
  • Cookie Policy
  • Terms
Copyright © 2023 Informa PLC. Informa PLC is registered in England and Wales with company number 8860726 whose registered and Head office is 5 Howick Place, London, SW1P 1WG.